I have a Mac as well, and I'm considering purchasing Windows 7 and running it on BootCamp considering that my University offers the Ultimate version for about $30. I can't really justify it yet though, since I don't own any games yet, and I'm a poor college student.

My best friend has a MAC, and I always tease her about it (hey, quad cores beat anything, right?), but I was excited to hear Bioshock was gonna get released for it. Finally! I now know what to get her for her birthday. :D